The invention is generally related to the field of resist patterning of semiconductor devices and more specifically to resist strip and resist residue removal processes.
In the fabrication of semiconductor devices, photoresist patterns are routinely used for delineating certain areas of the semiconductor device, for example, for patterned etching and ion implantation. After the etch or implantation sequence, the resist pattern must be removed. This is referred to as a resist strip. Additionally, any resist residue must also be removed. Currently, an ozonated H2SO4 operated at 130xc2x0 C. or a combined solution of H2SO4 and H2O2 are widely used for resist strip. To reduce particles, the above resist strip process is followed by a SC1 (H2O:NH4OH:H2O2) megasonic cleanup. Alternatively, a deionized water (DIW) scrub may be used for particle removal.
Unfortunately, the chemicals described above for resist strip are not environmentally safe and require special precautions for handling and disposal. Furthermore, sulfur compounds have been found to be left on wafer surfaces after the H2SO4 cleanups, which may cause corrosions or work function shifts on devices. The SC1 clean-up may result in NH3 abatement. If the alternative DIW scrub is used, two process tools are required. Accordingly, a resist strip and particle removal process is desired that is environmentally safe and overcomes the above mentioned particle removal problems.
U.S. Pat. No. 5,464,480 describes a process for removing organic materials such as photoresist without the use of H2SO4 and H2O2. Wafers are placed in a tank containing chilled deionized water. Ozone is diffused into the chilled deionized water to oxidize the organic material from the wafer surface. This process requires the addition of a chiller to current process equipment.
The invention is a method and apparatus for resist pattern strip and resist residue removal that uses an ozonated deionized water mist. An atomizer may be used to mix ozone and deionized water into a fine mist. The ozonated deionized water mist is then sprayed on the wafers.
An advantage of the invention is providing a resist strip and resist residue removal process that offers reduced processing time and that is environmentally safe.
This and other advantages will be apparent to those of ordinary skill in the art having reference to the specification in conjunction with the drawings.